A watch of this type is disclosed for example in EP Patent No, 1 396 766 A, incorporated herein by reference. In this type of watch, wherein a hand is used to display the instantaneous depth, a horological type stepping motor, called a Lavet motor, is generally used to drive the hand in rotation about its axis. However, the watch might lose motor steps, for example after the watch has been subject to shocks, i.e. there is a step shift between the electronic counter and the angular position of the hand. This phenomenon causes desynchronisation between the motor and the electronic control circuit, and thus an erroneous instantaneous depth display by the hand.
The instantaneous depth indication is vital to the diver. Consequently, this desynchronisation can endanger his health, since he will make the dive based on erroneous data, which could lead to him exceeding his physiological limits.
It is an object of the present invention to overcome these drawbacks.